Monitoring Alzheimer's patients for acute changes in cognitive functioning.

To develop and evaluate the use of cognitive monitoring for detecting episodes of acute, excess cognitive decline in individual Alzheimer's disease (AD) patients, the authors conducted six repeated cognitive assessments over 11 weeks on 41 otherwise healthy people with mild-to-moderate AD. Patients demonstrated stable cognitive performance over 11 weeks on seven standard neuropsychological tests. Prediction intervals quantitatively defined the expected limits of cognitive decline. They indicated with 90% certainty that over the 11-week period, healthy mild-to-moderate AD patients should not decline more than 4 points on the Word List Recall test, 3 points on the Digit Span test, or 8 items on the Digit Symbol or Verbal Fluency tests. The cognitive stability of healthy AD patients indicates that it is possible to monitor them for acute, excess cognitive decline.